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Abstract:

An SCP of a telecommunications network having a GMSC includes a network
interface unit of the SCP that receives a CAMEL transaction from the
GMSC. The SCP includes a processing unit, of the SCP, which controls the
CAMEL transaction relinquished by the GMSC and decides whether or not to
idle the CAMEL transaction during MTRR. A method for guiding a CAMEL
transaction by an SCP during MTRR having the steps of receiving at a
network interface unit of the SCP a CAMEL transaction from a GMSC. There
is the step of deciding by a processing unit of the SCP which controls
the CAMEL transaction relinquished by the GMSC whether or not to idle the
CAMEL transaction during MTRR.

Claims:

1. A Service Control Point (SCP) of a telecommunications network having a
Gateway Mobile Switching Centre (GMSC) comprising: a network interface
unit of the SCP that receives a Customized Application for Mobile
Enhanced Logic (CAMEL) transaction from the GMSC; and a processing unit
of the SCP which controls the CAMEL transaction relinquished by the GMSC
and decides whether or not to idle the CAMEL transaction during Mobile
Terminated Roaming Retry (MTRR).

2. The SCP of claim I wherein the network interface unit receives an
Event Detection Point (EDP)-T-BUSY message and the processing unit
decides whether to release the transaction, terminate the transaction or
continue with the transaction based on the EDP-T-BUSY message.

3. The SCP of claim 2 wherein the EDP-T-BUSY message is in a form of a
request and has an appropriate cause value indicating MTRR was
encountered at the GMSC.

4. The SCP of claim 2 wherein the processing unit sends through the
network interface unit a CAP defined operation called RELEASE CALL to
release the transaction.

5. The SCP of claim 2 wherein the processing unit rearms the EDP message
and sends through the network interface unit a CONTINUE message having a
suppress T-CSI indication so as not to retrigger CAMEL for the
transaction and so the transaction will continue.

6. The SCP of claim 2 wherein the processing unit sends through the
network interface unit an END message to terminate the transaction and
cause the GMSC to retrigger an HLR without CAMEL suppression.

7. A method for guiding a Customized Application for Mobile Enhanced
Logic (CAMEL) transaction by a Service Control Point (SCP) during Mobile
Terminated Roaming Retry (MTRR) comprising the steps of: receiving at a
network interface unit of the SCP a CAMEL transaction from an Gateway
Mobile Switching Centre (GMSC); and deciding by a processing unit of the
SCP which controls the CAMEL transaction relinquished by the GMSC whether
or not to idle the CAMEL transaction during MTRR.

8. The method of claim 7 including the steps of the network interface
unit receiving an Event Detection Point (EDP)-T-BUSY message and the
processing unit deciding whether to release the transaction, terminate
the transaction or continue with the transaction based on the EDP-T-BUSY
message.

9. The method of claim 7 wherein the EDP-T-BUSY message is in a form of a
request and has an appropriate cause value indicating MTRR was
encountered at the GMSC.

10. The method of claim 7 including the step of the processing unit
sending through the network interface unit a CAP defined operation called
RELEASE CALL to release the transaction.

11. The method of claim 7 including the steps of the processing unit
rearming the EDP message and sending through the network interface unit a
CONTINUE message having a suppress T-CSI indication so as not to
retrigger CAMEL for the transaction and so the transaction will continue.

12. The method of claim 7 including the step of the processing unit
sending through the network interface unit an END message to terminate
the transaction and cause the GMSC to retrigger and HLR without CAMEL
suppression.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application
No. 61/493551, filed Jun. 6, 2011, the disclosure of which is
incorporated herein by reference.

TECHNICAL FIELD

[0002] The present invention is related to guiding a CAMEL transaction by
an SCP during MTRR. (As used herein, references to the "present
invention" or "invention" relate to exemplary embodiments and not
necessarily to every embodiment encompassed by the appended claims.) More
specifically the present invention is related to guiding a CAMEL
transaction by an SCP during MTRR which controls the CAMEL transaction
relinquished by a GMSC and decides whether or not to idle the CAMEL
transaction during MTRR.

BACKGROUND

[0003] This section is intended to introduce the reader to various aspects
of the art that may be related to various aspects of the present
invention. The following discussion is intended to provide information to
facilitate a better understanding of the present invention. Accordingly,
it should be understood that statements in the following discussion are
to be read in this light, and not as admissions of prior art.

[0004] Today MTRR and CAMEL interaction is handled by the 3GPP
specifications by idling the CAMEL terminating transaction and restarting
it. The idea of this invention is to relinquish control of the CAMEL
transaction to the SCP and let the SCP decide whether to idle it or not.
This proposal also rectifies the way MTRR encountering is reported to the
SCP by reporting EDP-Abandon which is almost dedicated to the
originator's behavior of prematurely idling the call.

[0005] Today the CAMEL transaction is terminated due to MTRR interaction
and restarted stating that the mobile subscriber might need to have the
trigger happen again due to the change of location of the subscriber.

[0006] Problems with the existing solution include:

[0007] 1. An EDP (event detection point) is used to terminate the
relationship which is not very appropriate. EDP-Abandon is used. But
EDP-abandon pertains to the originator hanging up in the context of CAMEL
triggers.

[0008] 2. The whole transaction is idled without any consideration given
to the fact if the service running is a location sensitive service or
not.

[0009] 3. This can result in certain call architectures to create a lot of
basic call state machines between the first triggering call model and the
next triggering call model, although it is for the same party.

[0010] 4. The creation of additional call models can result in the
generation of redundant billing.

[0011] 5. The same call reference number can be reused and thus correlate
all the billing between the previous terminating MSC, the new terminating
MSC and the GMSC.

[0012] 6. For service interactions like caller ring back, the sequence of
ringing, silence (or generic ringing) and then personalized ringing again
can convey mixed feelings about the call status to the caller who might
inadvertently hang up.

BRIEF SUMMARY OF THE INVENTION

[0013] The present invention pertains to a Service Control Point (SCP) of
a telecommunications network having a Gateway Mobile Switching Centre
(GMSC). The SCP comprises a network interface unit of the SCP that
receives a Customized Application for Mobile Enhanced Logic (CAMEL)
transaction from the GMSC. The SCP comprises a processing unit of the SCP
which controls the CAMEL transaction relinquished by the GMSC and decides
whether or not to idle the CAMEL transaction during Mobile Terminated
Roaming Retry (MTRR).

[0014] The present invention pertains to a method for guiding a CAMEL
transaction by an SCP during MTRR. The method comprises the steps of
receiving at a network interface unit of the SCP a CAMEL transaction from
a GMSC. There is the step of deciding by a processing unit of the SCP
which controls the CAMEL transaction relinquished by the GMSC whether or
not to idle the CAMEL transaction during MTRR.

BRIEF DESCRIPTION OF THE DRAWING

[0015] In the accompanying drawings, the preferred embodiment of the
invention and preferred methods of practicing the invention are
illustrated in which:

[0016] FIG. 1 is a flow diagram regarding the present invention; and

[0017] FIG. 2 is a block diagram of an SCP of the present invention.

DETAILED DESCRIPTION

[0018] Referring now to the drawings wherein like reference numerals refer
to similar or identical parts throughout the several views, and more
specifically to FIG. 2 thereof, there is shown an SCP 10 of a
telecommunications network having a GMSC. The SCP 10 comprises a network
interface unit 12 of the SCP 10 that receives a CAMEL transaction from
the GMSC. The SCP 10 comprises a processing unit 14 of the SCP 10 which
controls the CAMEL transaction relinquished by the GMSC and decides
whether or not to idle the CAMEL transaction during MTRR.

[0019] The network interface unit 12 may receive an EDP-T-BUSY message and
the processing unit 14 decides whether to release the transaction,
terminate the transaction or continue with the transaction based on the
EDP-T-BUSY message. The EDP-T-BUSY message may be in a form of a request
and has an appropriate cause value indicating MTRR was encountered at the
GMSC.

[0020] The processing unit 14 may send through the network interface unit
12 a CAP defined operation called RELEASE CALL to release the
transaction. The processing unit 14 may rearm the EDP message and sends
through the network interface unit 12 a CONTINUE message having a
suppress T-CSI indication so as not to retrigger CAMEL for the
transaction and so the transaction will continue. The processing unit 14
may send through the network interface unit 12 an END message to
terminate the transaction and cause the GMSC to retrigger and HLR without
CAMEL suppression.

[0021] The present invention pertains to a method for guiding a CAMEL
transaction by an SCP 10 during MTRR. The method comprises the steps of
receiving at a network interface unit 12 of the SCP 10 a CAMEL
transaction from a GMSC. There is the step of deciding by a processing
unit 14 of the SCP 10 which controls the CAMEL transaction relinquished
by the GMSC whether or not to idle the CAMEL transaction during MTRR.

[0022] There may be the steps of the network interface unit 12 receiving
an EDP-T-BUSY message and the processing unit 14 deciding whether to
release the transaction, terminate the transaction or continue with the
transaction based on the EDP-T-BUSY message. The EDP-T-BUSY message may
be in a form of a request and has an appropriate cause value indicating
MTRR was encountered at the GMSC.

[0023] There may be the step of the processing unit 14 sending through the
network interface unit 12 a CAP defined operation called RELEASE CALL to
release the transaction. There may be the steps of the processing unit 14
rearming the EDP message and sending through the network interface unit
12 a CONTINUE message having a suppress T-CSI indication so as not to
retrigger CAMEL for the transaction and so the transaction will continue.
There may be the step of the processing unit 14 sending through the
network interface unit 12 an END message to terminate the transaction and
cause the GMSC to retrigger and HLR without CAMEL suppression.

[0024] In the operation of the invention, the present invention provides
for:

[0025] 1. render control to the SCP 10 to decide if the transaction should
be idled or not by using basic end;

[0026] 2. trigger MTRR using the catch-all EDP T-EDP-BUSY;

[0027] 3. define a cause value to be used in the reporting of EDP-BUSY to
indicate to the SCP 10 that this report is due to MTRR or include the
MTRR IE already defined in the MAP specifications;

[0028] 4. provide mechanism to Release the transaction only from the SCP
10 and leave the call unaffected;

[0030] In GSM/UMTS a basic mobile termination call irrespective of the
originator goes through a GMSC who queries the HLR to download
subscription information and the current location of the mobile
subscriber.

[0031] This is done via a 3GPP MAP defined method called SRI which is
responded to by the HLR with an SRI-Ack. This SRI-Ack can contain a
roaming number to terminate to the mobile in the right VMSC where the UE
is roaming, or can come back with CAMEL information in the form of T-CSI
(I am intentionally not involving other CAMEL information that can also
be downloaded to keep the scenario simple).

[0032] When CAMEL information is downloaded, a CAMEL trigger using CAP
protocol is done towards the SCP 10. This provides the SCP 10 to run some
services on behalf of the actual terminator (example: terminating
prepaid, personalized numbering system, caller ringback tone, etc.).

[0033] Post the receipt of the trigger SCP 10 can actually decide what to
do with the call. Either due to some service let the call terminate as
is, or forward the call, or connect to an IP IVR, or release the call, or
monitor the call for answer and disconnect to charge appropriately, or
based on location of the subscriber connect the caller to some other
number, any such decision is achieved via sending of an operation defined
by the CAP (3gPP 29.078) protocol.

[0034] In one embodiment, the decision of the SCP 10 is to continue
terminating to the same subscriber but monitor the call (i.e. possibly
for answer and disconnect events on the basic call). This causes the GMSC
to receive the CONTINUE (CAP operation) from the SCP 10 preceded by the
arming of detection points for answer and disconnect (via CAP operation
RRBE).

[0035] The receipt of the CONTINUE operation by the GMSC results in
sending another SRI to the HLR (but asking HLR not to send back the same
CAMEL information indicated via CAMEL suppression parameter (defined by
MAP 3GPP 29.002).

[0036] This results in the HLR sending a roaming number extraction message
to the V-MSC (where the UE is roaming currently) and receiving the
roaming number back from the V-MSC. The HLR in turn sends the roaming
number to the GMSC in the message SRI-Ack, as mentioned before.

[0037] Upon receipt of the roaming number the GMSC extends the call to the
V-MSC over the interconnect protocol between the G-MSC and the V-MSC.

[0038] When the V-MSC receives the call it starts to page the UE. While
paging has been started, the UE might actually have decided to fallback
(CSFB-3GPP 23.272) to another V-MSCn. This results in the HLR being
notified by the new V-MSCn that CSFB is going on. This prompts the HLR to
send either a CANCEL location to the old V-MSC (or SEND-ID is received by
the old VMSC in case of supercharger).

[0039] The old V-MSC then sends back an RCH (resume call handling) to the
GMSC. The RCH message is the same that is used for optimal routing
functionality but with indications of MTRR.

[0040] Upon receipt of this the GMSC that was running a CAMEL transaction
on behalf of the real terminator, idles the CAMEL transaction and
restarts a new one by downloading the CAMEL information again via the
triggering of SRI (without camel suppression indication).

[0041] This causes the CAMEL transaction to restart.

[0042] This invention does not change up until the RCH method receipt at
the GMSC.

[0043] Once the RCH is received instead of reporting ERB-Abandon to the
SCP 10 this disclosure recommends to report ERB-T-BUSY.

[0044] EDP T-BUSY should always be armed in the form of Request (and not
notification). EDP-T-BUSY should be populated with an appropriate cause
value indicating MTRR was encountered at the GMSC (due to the receipt of
RCH specific to MTRR).

[0045] SCP 10, the controller of the service can now decide what should be
the fate of the call. Either release the call, or continue with the call
or terminate the transaction.

[0049] SCP 10 can rearm EDPs as some would have been disarmed upon
reporting T-BUSY and send back a CONTINUE (or CONTINUE with arguments).

[0050] Because SSF knows that the trigger was for MTRR, the receipt of
CONTINUE allows the call to proceed unaltered.

[0051] Case 3: Idle the Transaction

[0052] SCP 10 can send a basic end to terminate the transaction. This
would cause the GMSC to retrigger SRI towards the HLR without CAMEL
suppression.

[0053] The present invention prevents reporting of the incorrect EDP
Previously, the EDP being reported erroneously indicated that the calling
party has prematurely abandoned the call, by reporting EDP-Abandon. The
present invention corrects this problem by providing the correct EDP
report to the SCP and thereby allows the SCP to control the fate of the
call.

[0054] In the present invention, the cause value can be replaced by MTRR
indication as is used in the RCH message and other MAP messages like SRI
to indicate MTRR was encountered. Instead of relying on the cause value,
a special parameter can be put in the extension container that will
safely interwork with any node (who will ignore this parameter if it is
not understood). This provides another means of communicating from the
GMSC to the SCP that MTRR has taken place.

[0055] The present invention prevents creation of more basic call models
on the GMSC. By releasing the call and creating another trigger for the
same terminating subscriber, it is possible to use up more resources on
the triggering node the GMSC by creating more call models. With the
present invention, with the control provided to the SCP to decide if the
transaction should continue or not, this extra resource utilization can
be reduced by reusing the same call model to continue the call.

[0056] The present invention prevents excessive billing information. The
creation of call models results in the generation of billing information
from each call model. This can be reduced as well with the present
invention.

[0057] The present invention allows for the use of the same call reference
number to correlate billing in the downstream billing processor. When
billing is generated, a unique number is used to correlate the billing
being generated from different nodes. By means of this idea, using the
same unique number results in easier correlation than what currently
exists, where for a single call and for a single party multiple billing
correlation numbers are generated.

[0058] Specifications related changes in regard to the present invention.

[0059] 1. MTRR IE to be added in the Event Report BCSM state machine
method. Affected specifications 3GPP 23.078, 29.078. Reporting of T-BUSY
due to MTRR in 23.078. Support of MTRR IE in the CAP protocol in 29.078.
The parameter is being proposed as optional. For backwards compatibility
nodes adhering to this invention can continue to follow the same process
as today, which is reporting of EDP-Abandon.

[0060] 2. Basic call handling 3GPP 23.018-based on this invention if the
initial CAMEL transaction is maintained even during MTRR, then the SRI
following the procedures of MTRR, will contain suppress T-CSI indication
so as not to retrigger CAMEL for the same party from the GMSC. The
inclusion of triggering of the T-BUSY EDP also has to be shown.

[0061] 3. 3GPP 23.272 CS fallback--changes similar to 3GPP 23.018 has to
be reflected in the MTRR procedures.

[0062] Advantages of the Invention

[0063] 1. Prevents reporting of the incorrect EDP.

[0064] 2. Reporting the information correctly via T-BUSY (with appropriate
cause value). The cause value can be a mutual agreement between different
nodes.

[0065] 3. The cause value can be replaced by MTRR indication as is used in
the RCH message and other MAP messages like SRI to indicate MTRR was
encountered.

[0066] 4. Prevents creation of more basic call models on the GMSC.

[0067] 5. Prevents excessive billing information.

[0068] 6. Re-use of the same call reference number to correlate billing in
the downstream billing processor.

[0069] 7. Provides a control on the service logic basis whether to idle
CAMEL transaction or not.

[0070] Abbreviations

[0071] GMSC--Gateway Mobile Switching Centre

[0072] HLR--Home Location Register

[0073] SCP--Service Control Point

[0074] ERB--Event Report BCSM

[0075] BCSM--Basic Call State machine

[0076] MTRR--Mobile Terminated Roaming Retry

[0077] SRI--Send Routing Information

[0078] RCH--Resume Call handling

[0079] EDP--Event Detection Point

[0080] RRB--Request Report BCSM

[0081] MSC--Mobile Switching Centre

[0082] V-MSC--Visited MSC

[0083] CAP--CAMEL Application protocol

[0084] CAMEL--Customized Application for Mobile Enhanced Logic

[0085] MAP--mobile application protocol

[0086] SSF--Service Switching Function

[0087] References, All of Which Are Incorporated by Reference

[0088] 3GPP 29.002

[0089] 3GPP 23.272

[0090] 3GPP 23.078

[0091] Although the invention has been described in detail in the
foregoing embodiments for the purpose of illustration, it is to be
understood that such detail is solely for that purpose and that
variations can be made therein by those skilled in the art without
departing from the spirit and scope of the invention except as it may be
described by the following claims.